difference between uhf and vhf +++its distance

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youssef_electronic

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heloo guys i want know the difference between vhf and uhf ??????+++The kind that you advise me to him VHF or UHF and I also want to distance and distance of uhf vhf ??????

N4KVE

Member
In a downtown area with lots of buildings, UHF will give better penetration & work better. In an area with no hills, & no buildings with just flat terrain, VHF will go further, so it really depends where you are. The higher you go in freq, the less distance, but more penetration you will have. That's why some states with huge wide open spaces still use lo band. [30-50]. GARY N4KVE

zz0468

QRT
Banned
As soon as you try to characterize any frequency band in terms of sheer distance, you're going to be wrong. There's too many variables. Free space path loss goes up with frequency, but for a given size, so does antenna gain, so in some circumstances, the antenna gains can increase faster than the path loss does.

To the OP, it's clear that English is not your native language. try to clarify you question so we can answer it better. In general, though, UHF bounces around easier than VHF, but absorption by trees and buildings is higher. What would work best for you is entirely dependent on what you're trying to accomplish.

youssef_electronic

Member
but the distance of the uhf and vhf of this radio it's multi band vhf and uhf ????, pleeez becaus I understood is how to use this calculator take the information of this radio multi band http://icom-france.com/produit-ic-e92d.php

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RodStrong

Member
In a downtown area with lots of buildings, UHF will give better penetration & work better. In an area with no hills, & no buildings with just flat terrain, VHF will go further, so it really depends where you are. The higher you go in freq, the less distance, but more penetration you will have. That's why some states with huge wide open spaces still use lo band. [30-50]. GARY N4KVE

^^^^^^This^^^^^^

This is a simple and general explanation that works. No need to get any more techincal than this.

KC4RAF

Member
Another in agreement with MOONBOOTS.

The shorter wave length do better in and around buildings, etc. Long wave open range.

zz0468

QRT
Banned
Wow. Two posts and hes out.

zz0468

QRT
Banned
The shorter wave length do better in and around buildings, etc. Long wave open range.

It's just not that simple. If that was true, the need for 800 MHz BDA systems to provide in-building coverage wouldn't exist as much as it does.

Smaller wavelengths bounce better, and can couple into smaller openings, but that advantage is lost in absorption. The tinted glass on a high rise can have 10db of attenuation at VHF and UHF, and 50 db attenuation at 800 MHz. I know - I've measured some. The lower frequencies refract around mountains and hills better. In open areas, you're more likely to be dealing with just free space loss.

I've seen plenty of wide area 800 or 900 systems that talk forever from a single site, and plenty of urban VHF systems with kickas* in-building coverage.

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